A role for alpha- and beta-catenins in bacterial uptake

Interaction of internalin with E-cadherin promotes entry of Listeria monocy togenes into human epithelial cells. This process requires actin cytoskelet on rearrangements. Here we show, by using a series of stably transfected ce ll lines expressing E-cadherin variants, that the ectodomain of E-cadherin is sufficient for bacterial adherence and that the intracytoplasmic domain is required for entry. The critical cytoplasmic region was further mapped t o the beta-catenin binding domain. Because beta-catenin is known to interac t with alpha-catenin, which binds to actin, we generated a fusion molecule consisting of the ectodomain of E-cadherin and the actin binding site of al pha-catenin. Cells expressing this chimera were as permissive as E-cadherin -expressing cells. In agreement with these data, alpha- and beta-catenins a s well as E-cadherin clustered and colocalized at the entry site, where F-a ctin then accumulated. Taken together, these results reveal that E-cadherin , via beta- and alpha-catenins, can trigger dynamic events of actin polymer ization and membrane extensions culminating in bacterial uptake.